The antiviral lectin Griffithsin (GRFT) has broad spectrum activity against human immunodeficiency viruses (HIV) types 1 and 2, herpes simplex virus type 2 (HSV-2) and hepatitis C virus (HCV) (1-4). Griffithsin-based topical microbicide formulations offer the potential for use as a multipurpose, non- antiretroviral based method to prevent HIV-1 and epidemiologically linked infections. The Project 2 objective is to show that GRFT containing rectal microbicide products are safe and effective in the Rhesus macaque model of rectal HIV transmission. These studies are designed to be complementary to the human clinical studies proposed in Project 3. We have three specific aims: Aim 1 is to evaluate the safety, pharmacokinetics and pharmacodynamics (PK/PD) of GRFT carbopol gel. We will conduct a three stage placebo controlled PK/PD study in adult male Rhesus macaques with the GRFT rectal gel formulation and matched placebo gel supplied by Core B. The proposed macaque study is designed to address specific translational questions concerning immunotoxicity and health of the mucosal environment after GRFT exposure. Favorable stage 1 outcomes include detection of active HIV-1 inhibitory concentrations of GRFT in rectal fluids and acceptable clinical safety metrics, which allows progression to the efficacy Stage 2. Using a cohort of GRFT treatment experienced animals will allow us to determine whether pre-existing immunity to GRFT affects product efficacy. Stage 3 will test the GRFT and placebo products in SHIV infected animals, where we will compare amounts of virus shed in experimental versus control animals, providing an additional safety metric. Aim 2 is to assess the impact of GRFT treatment on the mucosal immune environment. We will use multiplexed immunoassays and gene expression arrays to measure markers of inflammatory immune responses. The highly sensitive immunohistochemistry (IHC) techniques refined in Prof. Kristina Broliden's laboratory will be applied to compare the number, distribution and activation state of HIV target cells and expression of HIV receptor targets CD4, CCR5, DC-SIGN and Langerin plus markers of epithelial integrity in rectal biopsies from animals treated with GRFT active drug or matched placebo. Flow cytometry analyses will also enumerate and phenotype lymphocytes in biopsy tissues. Aim 3 is to assess the impact of GRFT treatment on the mucosal environment in the rectum using a systems biology approach that utilizes modern mass spectrometry proteomics assays to compare tissues and rectal secretions from animals that receive active drug versus placebo, and to evaluate the effect of GRFT treatment on the rectal microbiota of treated animals.